How to use

isReference

method

in

com.mxgraph.io.mxChildChangeCodec

@Override
public Node afterEncode(mxCodec enc, Object obj, Node node)
{
  if (obj instanceof mxChildChange)
  {
    mxChildChange change = (mxChildChange) obj;
    Object child = change.getChild();
    if (isReference(obj, "child", child, true))
    {
      // Encodes as reference (id)
      mxCodec.setAttribute(node, "child", enc.getId(child));
    }
    else
    {
      // At this point, the encoder is no longer able to know which cells
      // are new, so we have to encode the complete cell hierarchy and
      // ignore the ones that are already there at decoding time. Note:
      // This can only be resolved by moving the notify event into the
      // execute of the edit.
      enc.encodeCell((mxICell) child, node, true);
    }
  }
  return node;
}

@Override
public Node afterEncode(mxCodec enc, Object obj, Node node)
{
  if (obj instanceof mxChildChange)
  {
    mxChildChange change = (mxChildChange) obj;
    Object child = change.getChild();
    if (isReference(obj, "child", child, true))
    {
      // Encodes as reference (id)
      mxCodec.setAttribute(node, "child", enc.getId(child));
    }
    else
    {
      // At this point, the encoder is no longer able to know which cells
      // are new, so we have to encode the complete cell hierarchy and
      // ignore the ones that are already there at decoding time. Note:
      // This can only be resolved by moving the notify event into the
      // execute of the edit.
      enc.encodeCell((mxICell) child, node, true);
    }
  }
  return node;
}